What are Nodes and Clients in Ethereum?

Ethereum is the distributed blockchain network of computers running software that can verify blocks and transactions. The software is known as a client that must be running into an Ethereum Node. The following article discusses the following topics of Ethereum Node and Ethereum Client:

1. What is Ethereum Node?
2. Types of Ethereum Node
3. What is Ethereum Client
4. Types of Ethereum Client
5. Ethereum Node vs Ethereum Client

Let’s start discussing each of these topics in detail.

What is Ethereum Node?

An Ethereum node is a computer that is running the software client. The blockchain network is made up of nodes, which are the only method to access it. Nodes communicate with one another in order to validate transactions and record data about the status of the blockchain. On the Ethereum network, these computers or servers are responsible for storing, validating, and trading data.

• Each node keeps its own copy of the blockchain and strives to verify that it matches the copies of all the other nodes. 
• Every node on the network must process any action that requires a new block to be added to the blockchain. 
• This network of continually communicating nodes allows us to avoid relying on a single source of truth and all of the challenges it entails. 
• A new block is added based on whether or not the majority of nodes accept it.

Types of Ethereum Nodes

Ethereum Nodes are a system that operates in a Point to Point network model. There are 3 types of Nodes:

1. Full Node: The responsibility of a full node is to verify and validate each and every transaction that takes place inside the network and maintain the state of the blockchain. When a smart contract transaction occurs, full nodes also execute all of the instructions in the smart contract. It determines whether or not the smart contract execution is producing the expected results. These nodes maintain a full copy of the blockchain data.

• It keeps receiving copies of the entire blockchain including its transactions which are stored locally and keeps the latest state of transaction with itself. 
• When a smart contract transaction occurs, full nodes also execute all of the instructions in the smart contract. 
• It determines whether or not the smart contract execution is producing the expected results. 
• Consider an example where person A performs a transaction to person B, this transaction is added to the blockchain, then the full nodes verify whether the transaction complies with all the Ethereum specifications, and maintain the latest state of the blockchain by storing or removing the specification if it does not comply.
• An example of a discarder transaction is when a person transfers X ETH to another person but their account contains less ETH.

2. Archive Nodes: Archive nodes are complete nodes that have the “archive mode” option enabled. While a Full Node only stores the latest state of the transaction, the Archive nodes hold all of the blockchain’s history data dating back to the genesis block. 

• The Archive node is used when blocks prior to the latest 128 blocks are required. 
• For example, using functions like eth_getBalance of a historic address would require an archive node, as will interacting with smart contracts launched far earlier in the blockchain.
• Because of its special feature, Archive Nodes require more than 6 Terabytes of space, contrary to Full node which only requires a little over 500 Gigabytes of diskspace. 
• So, it can be inferred, that archive nodes are not useful for average people, they are effective in the application of block exploring, wallet vending, and chain analytics.

3. Light Nodes: A light node, unlike a full node, does not hold the complete current blockchain state and stores only the block header. It is suitable for low memory and computational devices since maintaining a light node involve the least investment in hardware, running costs, and technical skill. 

• Light nodes rely on full nodes to function. 
• These nodes do not need to run continuously or read and publish a large amount of data on the blockchain. 
• It provides an easy way to create a wallet, especially for beginners. 
• For example, Solid-State Drives cannot afford to store the gigabytes of data that other nodes take. 

But there are some limitations of light nodes which cannot be denied, there is no guarantee that the light wallet provider will be online when it is needed.

What is Ethereum Client?

An Ethereum client is a software program that is used to implement the Ethereum specification and connect itself with other Ethereum clients over a peer-to-peer network. Different Ethereum clients can communicate with one another if they follow the reference specification and the defined communication protocols. While these many clients are created by various teams and in various programming languages, they all “speak” the same protocol and adhere to the same rules. As a result, they may all function on and interact with the same Ethereum network.

• These interactions among different clients in the network take place using various programming languages like Geth (Go), OpenEthereum (Rust), Nethermind (C#, .NET), Besu (Java), Erigon (Go/Multi).
• The yellow paper is the Ethereum protocol that allows anybody to run a client to construct a node. 
• The formal requirements that comprise Ethereum distinguish the blockchain from Bitcoin. Whereas Ethereum sets standard behaviors that all Ethereum clients must adhere to, Bitcoin Core does not. Ethereum’s specs enabled the blockchain to allow for different, but interoperable, software implementations of an Ethereum client by providing standard documentation and simple language.

Types of Ethereum Clients

There are 3 types of Ethereum Clients

1. Full Client: Full clients save the complete Ethereum blockchain, which might take several days to synchronize and takes a massive amount of disc space – more than 1 Terabyte, according to the most recent estimates. Full clients enable connected nodes to conduct all network functions, including as mining, transaction and block-header validation, and smart contract execution.

2. Light Client: Ethereum clients do not always need to necessary keep all of the data, so often, when data storage and performance are concerns, developers utilize the “light clients”. Light clients provide a portion of full client capability. Because light clients do not keep the entire Ethereum blockchain, as a result, they can provide quick delivery and free up data storage space.

• The functionality of a light client is adapted to the purposes of the Ethereum client. 
• Light clients, for example, are widely used within wallets to maintain private keys and Ethereum addresses. 
• They also manage smart contract interactions and transaction broadcasts. 
• Light clients are also useful for web3 instances within JavaScript objects, Dapp browsers, and obtaining the exchange rate data.

3. Remote Client: A remote client is much like a light client. The primary distinction is that a remote client does not keep its own copy of the blockchain or validate transactions or block headers. Remote clients, on the other hand, rely entirely on a full or lite client to have access to the Ethereum blockchain network. These clients are mostly used as wallets for transmitting and receiving transactions.

Ethereum Node vs Ethereum Client 

Below are some of the differences between Ethereum Node and Ethereum Client.

S. No.	Ethereum Node	Ethereum Client
1.	A machine running Ethereum client software is referred to as an “Ethereum Node”.	A client is an Ethereum implementation that validates all transactions in each block, ensuring the network’s security and data accuracy.
2.	The three types of Ethereum Nodes are Full, Light, Archive, and Miner Nodes.	The three types of Ethereum Clients are Full, Light, and Remote Clients.
3.	The Ethereum node operating system allows us to access the internet.	The Ethereum client computer allows a user to access the node operating system.